We propose an approach to timbral remapping, a process which maps the timbre variations of one audio source onto the timbre variations of another, for real-time control of synthesis. Puckette (ICMC, 2004) has made a foray into such a concept, but there are two important issues which must be addressed: how best to construct the timbre space for remapping purposes; and how to perform this remapping eficiently in real-time. We review some of the acoustical features used in the literature to represent timbre, and consider how to combine these usefully. We also describe some of our recent work on warping timbre space for effective coverage, and on an optimised real-time database lookup procedure suitable for use in live remapping.